The VSYM service updates the value of dialog variables found in the function pool by resolving the values of any system symbols. This includes all system static symbols and dynamic symbols and any user-defined static symbols. The z/OS MVS Initialization and Tuning Reference has details on system static and dynamic symbols. Consult your system programmer for any locally defined user symbols as these are system and installation dependent If the named dialog variable is not found in the function pool, it is not created.